B210sleeper, thanks for the picture.
It's as I thought. I think that you will find that the warm air thing is for more than just startup & is in operation most of the time. The cold air ducting from the front is an improvement from the earlier system when it drew so called cold air, from under the bonnet.

Many carmakers were drawing cold air from outside the engine bay by the time the 80's rolled around, but like I said earlier, I think you will find that the warm air is operational all the time untill a certain temperature is reached inside the air cleaner housing when the cold air is admited instead, although I think the thermostat control was able to control a mixture of hot & cold air to stabilise the temperature of the air passing into the carb